北大OJ2262

#include<iostream>
#include<cstdlib> 
#include<cstdio> 
#include<cstring> 
#include<algorithm>
#include<cmath> 
using namespace std; 
bool isprime ( int k ) 
{     
	int t = sqrt ( k + 0.5 ) ;
	for ( int i = 2  ; i <= t ; i ++ )
		if ( k % i == 0 )
            return false ;
		return true ;
 }
int main() 
{     
	 int n ;
	 while ( scanf ("%d", &n) , n )
     {        
		 int i ;        
		 int t = n / 2 ;
         for ( i = 3 ; i <= t ; i += 2 )
			 if ( isprime ( i ) && isprime ( n - i ) )
                 break ;
			 printf ( "%d = %d + %d\n" , n , i , n - i ) ;     
	 }
     return 0;
 }